Just curious? I think he could have still won the election without calling a referendum on the EU. The whole issue of 'shy' tories coming out in force to elect the Conservatives as the major governing party.
That said, it was the first time a new generation would be able to decide on their future in the EU - make what you will of exit polls in that most people who will have to deal with the consequences voted to remain but do you think that the referendum was needed in the first place?